How to Identify Rainwater Killifish

To identify Rainwater Killifish (Lucania parva), look at these key features.

Physical Characteristics

Body shape

elongated

Coloration

Generally pale, translucent olive to yellowish-brown dorsally, fading to silvery-white on the ventral side. Males often exhibit a yellowish or orange tint on their fins, particularly during breeding season, and may have a faint lateral stripe. Females are typically plainer.

Scale type

cycloid

Mouth position

superior

Distinctive features

Small size, typically not exceeding 6 cm (2.4 inches) in total length., Slender, somewhat compressed body., Relatively large eyes., Absence of a lateral line., Dorsal fin origin posterior to the anal fin origin.

Dorsal fin

Single dorsal fin, typically with 6-8 rays, originating behind the anal fin origin.

Tail fin

Rounded to slightly emarginate caudal fin.

Pectoral fin

Small, rounded pectoral fins.

Distinctive fins

Pelvic fins are small and located abdominally. Anal fin is relatively long, with 9-12 rays.

Identification Tips

1. 1

   Size and Shape

   Look for a small, slender fish, usually under 6 cm, with a somewhat compressed body.

2. 2

   Fin Placement

   Note that the dorsal fin originates distinctly behind the origin of the anal fin. This is a key distinguishing feature from many other killifish.

3. 3

   Coloration

   Observe the pale, olive-brown to yellowish body with a silvery belly. Breeding males may show yellowish or orange fins.

4. 4

   Mouth

   The mouth is upturned (superior), indicating a surface feeder.

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